Glossary of Diagnoses and Terminology

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Chromosomal translocation

Chromosomal translocation refers to an unusual arrangement of chromosomes which occurs as a result of genetic mutations inherited from the mother or father or as a result of changes that occur at the time of conception. It is estimated that about 1 person in 500 people has a translocation.

The two main types of translocations are reciprocal translocations, which occur when a piece of two different chromosomes break off and switch places, reattaching to the different chromosome, and Robertsonian translocations which occur when a chromosome from one pair attaches to a chromosome from another pair.

When a translocation occurs, but no chromosome material is lost or gained, this is called a balanced translocation. When chromosome material is lost or gained in the process of rearranging, this is called an unbalanced translocation.

Parental genetic testing and fetal karyotype testing can provide insight into the type and underlying cause of a fetal chromosome translocation. [16]